ChipMusic.org - DMG hum

Re: DMG hum

2013-01-03T20:45:56Z

is the volume pot in dmgs just a run of the mill part that I could pick up at radio shack or somewhere similar?

Re: DMG hum

2013-01-03T20:17:16Z

well I inspected the caps and replaced them: nothing

I think maybe it could be the headphone jack itself or the volume pot?

because the hum comes through the speaker and the factory headphone jack but not the prosound jack. plus the you can hear scratchiness when you turn the pot and when its set at the highest setting sometimes sound cuts out completely.

i thought maybe the batteries because I use rechargeables and they're old so I tried different ones same problem.

Re: DMG hum

2012-12-30T17:18:45Z

Yeah I mean I inverted the polarity once, being the same circuit, and the capacitor staying the same, but after having some current in the wrong way for a rather short period of time, it never worked the same, being in the correct position and with the circuit working normal. It modified the sound completely (to a rather bad way).

Try switching the caps, yes. It's not a big deal economically, and anyways the least you can get is improve the life of your DMG sound.

Re: DMG hum

2012-12-30T16:56:33Z

DogTag wrote:

Long ago happened to me that I reversed the polarity of a circuit by accident (which had one electrolytic) and after that it never sounded the same (though it kept working).

did you ever change that cap back to normal and did it sound the same after that?

maybe I'll switch the caps out for the hell of it.

and I forgot to mention that I switched the power LED to white and this is a play it loud

Re: DMG hum

2012-12-30T16:34:09Z

Grymmtymm wrote:

I don't remember if I changed them out or not its been awhile since I modded this one.
lets say I did if I reversed any of them could that be it? or would it even function if I reversed any of the caps?

I know very little about the DMG hardware, but for sure I can tell you that if you reversed the polarity of an electrolytic cap (the ones with polarity), it will for sure not work properly.
Long ago happened to me that I reversed the polarity of a circuit by accident (which had one electrolytic) and after that it never sounded the same (though it kept working).

Re: DMG hum

2012-12-30T16:11:42Z

I don't remember if I changed them out or not its been awhile since I modded this one.

lets say I did if I reversed any of them could that be it? or would it even function if I reversed any of the caps?

Re: DMG hum

2012-12-30T15:59:20Z

yes its this one gameboy

Re: DMG hum

2012-12-30T15:47:05Z

Is it only with this one particular gameboy? you dont have a ground loop or something?

Re: DMG hum

2012-12-30T15:46:10Z

it could possibly, if you haven't switched them out and they are stock (even in a Play It Loud!), they are *technically* past their expected life span.

its sort of amazing what recapping can fix. and, i should have caps back in stock asap, just waiting on one of them thats backordered.

Re: DMG hum

2012-12-30T15:44:30Z

could this have anything to do with the capacitors?

Re: DMG hum

2012-12-29T17:38:11Z

Im not near a camera at the moment but I'll take a pic ASAP.

everything works fine. only the speaker hum. and it's been awhile since I modded this gameboy so I can't really say that the hum wasn't there to begin with but to my best memory it wasn't.

it's a really clean gameboy I was impressed when I got it how clean it was I put the mods in and closed it up and haven't bothered with it til now because everything worked and I don't like opening them unless I have to because of the stress on the ribbon cable.

Re: DMG hum

2012-12-29T17:32:50Z

hmmm.

then check your solder points again for a short. or post pics of your work and we can check it out.

the half clock board is working right? just the speaker hum is the only issue you're noticing?

the only other thing I know to do would be to work through each mod, disconnecting it from the other circuitry, and do process of elimination. i was thinking the clock signal was getting into your audio path somehow and you were hearing it as the hum. but maybe not. as a generator of the hum, i suppose.

the other kits, the parts themselves, wouldn't do this. poor soldering can cause all sorts of issues. also in the backlight installation, something could have been damaged on the front PCB or any number of things. if it were me, and i wanted to get this figured out quick and not worry about it again, i'd just go through each mod, disconnect it, and see if it fixed the issue. start with the clock, then backlight, then prosound.

a ton of people have used similar configurations in their DMGs and gotten no issue, so i'm sure its not a compatibility issue.

check the tutorials again, and make sure you hooked everything up right of course.

and to just ask.... are you positive the hum wasn't there to begin with?

Re: DMG hum

2012-12-29T17:26:17Z

just the board and the switch inside this gameboy.

a regular spdt switch located on the right side of the shell in the empty space about 2" inches above the speaker and the board is right behind the screen, resting above that copper shield.

nowhere near the speaker.

Re: DMG hum

2012-12-29T17:25:02Z

just the board and the switch inside this gameboy.

a regular spdt switch located on the right side of the shell in the empty space about 2" inches above the speaker and the board is right behind the screen, resting above that copper shield.

nowhere near the speaker.

Re: DMG hum

2012-12-29T17:17:30Z

and you removed the original crystal right, and aren't wiring up some crazy switching mechanism, right?

(just to check)

it might be where you've located the easy_CLK board itself, the speaker's magnet might be picking up hum from that. try moving it somewhere else inside the case, away from this magnet.